When was your last period?

You've made the exciting decision to try to get pregnant (congratulations!) and you want to do everything you can to make it happen fast. Go, mama!

Use the ovulation calculator above to help pinpoint your most fertile days, giving you the best chance of starting or expanding your family now.

What Is an Ovulation Calculator?

Also known as an ovulation calculation, ovulation calendar, ovulation tracker, conception calculator, fertility calendar, or fertility calculator, this tool takes into account your average cycle length and luteal phase to give the most accurate fertility window for you. This ovulation calculator doesn’t just give you an estimate based on other women’s averages, it lets you plug in your own numbers to customize it for your own cycle.

What Is a Luteal Phase?

The luteal phase is the second half of your menstrual cycle beginning at ovulation and ending with a new period or pregnancy. This is when you have a huge surge of three important hormones:

Follicle stimulating hormone: Is released into your bloodstream by the pituitary gland to stimulate ovarian follicles to secrete estrogen and produce a mature egg (or two in the case of twins).

Luteinizing hormone: Is also released into your bloodstream by the pituitary gland in response to the rising estrogen levels. This important hormone triggers the ovarian follicle to release the egg(s) for potential fertilization.

And Progesterone: While estrogen plummets with ovulation, progesterone begins its climb to help nourish and thicken your uterine lining for potential egg implantation. Your progesterone levels will continue to rise if you become pregnant as it literally helps to “pro-gest” your fertilized egg!

On average, the luteal phase is 14 days long (half of an average 28-day cycle) nut “normal” is considered anywhere from 12 to 16 days. You can track your ovulation symptoms to better pinpoint how long your luteal phase is or simply pee on these ovulation strips.

If your luteal phase is less than 10 days, you’ll want to work with a holistic doctor to help boost your body’s progesterone production (see some tips here). With too short of a luteal phase, the fertilized egg may not be able to make it down the fallopian tubes into the uterus to implant before your period comes making pregnancy much more difficult.

Illustration credit from Algonquin College

How Many Days After Your Period Do You Ovulate?

On average, a woman will ovulate about 14 days after her period begins. This is based on a 28-day cycle length and a 14-day luteal phase. If your cycle (or luteal phase) is a different length from the average, you’re better off counting backward 14 days from the next projected period.

For example, if your cycle is 30 days long, you would ovulate 16 days after your period begins. Likewise, if you have an average 28-day cycle but your luteal phase is 16 days, you would ovulate 12 days after your past period began. This can all get a bit confusing, which is why an ovulation calculator is such a great tool. Just plug in your information and let the calculator determine your most fertile days, which are unique to your body.

Do You Ovulate Every Month?

While cycle lengths vary, most women will ovulate or release an egg every month. Not ovulating every month could be a sign of an underlying condition that should be discussed with your health care professional. However, stress can cause an occasional “missed” ovulation as well, so be sure to find ways do de-stress regularly to get (or keep) your cycle back on track. There are also many natural ways to balance hormones and prepare for pregnancy, so don’t give up hope if you’re unbalanced now. Just start doing footwork to get yourself back to homeostasis.

When Are You Most Fertile?

You are most fertile on the day you ovulate, however, because sperm can survive up to 5 days and the egg can survive up to 24 hours, your fertility window is more like 6 days long. Think of it like a wave. Your fertility begins to increase on day 10, then it peaks on day 14, and drops back down within a day or two. I got pregnant on day 11 and 13 of my 14 day ovulation cycles.

When Should I Ovulate?

You may be wondering: When do I ovulate? (You can learn about the typical signs here.) Ideally, a woman will ovulate 14 days before her next expected period. If your cycle is unusual or you know that your luteal phase is more or less than 14 days, this may be different for you. To find out when you should ovulate, you need to pay close attention to your body.

First you need to figure out your average cycle length. If it’s unpredictable, a trip to your health care provider can be helpful to rule out any underlying medical issues that might be affecting your cycle. Next, you should calculate your luteal phase by paying attention to ovulation signs and symptoms. Once you have that information, you can enter it into the ovulation calculator to get a much better idea of when you should be trying to conceive.

How Do You Calculate Your Fertile Days?

To calculate your most fertile days, you must first calculate the average length of your cycle. Then, you will need to know your luteal phase to calculate the days around ovulation in which you will be the most fertile. Assuming an average luteal phase of 14 days, your fertile days will be 13 to 18 days before your expected period. For a 28-day cycle, this would be days 10 to 16. Using an ovulation calculator can help you find your most fertile days more easily.

How Do You Calculate Your Ovulation Day?

Calculating your ovulation day is a bit simpler because ovulation only occurs on one day each month. Assuming a luteal phase of 14 days, your ovulation day will be 14 days before your next expected period. For a 28-day cycle, your egg would be released on day 14. If your luteal phase or cycle length are different than the average, plug your information into the ovulation calculator to get your specific ovulation and fertility predictions.

What Are the “Safe Days” After Your Period?

For someone looking to avoid pregnancy, many health care professionals would say there are few truly “safe” days, especially if your periods are irregular. That being said, the chances of pregnancy are much lower during your period and possibly a few days after depending on your cycle and period length. For a 28-day cycle and a period length of 6 days, there are only 4 days before your fertility window opens — however, it’s possible to get pregnant then, too. There’s also good reason to continue to have sex even when fertility is low. Some studies show the health benefits of having regular sex, including a more regular cycle!

How Long Does it Take to Get Pregnant After Your Period?

On average, women ovulate on day 14 of their menstrual cycle, but their fertile days are from day 10 to 16. That means it would be about a week after your period ends when an egg is released so you can become pregnant during sex, but you may not know you are pregnant for another 2 weeks after that (at the time of a missed period and positive pregnancy test). Some women know they are pregnant before they get that BFP based on some symptoms.

That being said, variation in cycle length is not uncommon and should be taken into account. For example, if you have a 24-day cycle and a period that lasts 6 days, the end of your period will run up against the beginning of your fertile window, meaning you could conceive as soon as your period ends.

Ovulation Calculator: Can You Still Have a Period and Not Ovulate?

Yes. Some researchers believe that as much as 30% of regular cycles are anovulatory (no ovulation occurs). It is possible to have no signs of anovulation (meaning you have a regular cycle) but still be experiencing it. If you’re concerned that you may not be ovulating, talk to your health care provider.

What Is the Fertile Window?

Your fertile window is the time during your cycle that intercourse is more likely to end in conception. The fertile window depends on your cycle and your luteal phase length, therefore, it’s different for everyone. Using an average cycle length (28 days) and luteal phase (14 days), your fertile window would be days 10 to 16 of your cycle.

How Long Is the Window for Ovulation?

Ovulation only occurs one day each month. The egg that is released can only survive for 12 to 24 hours, so the ovulation window is very small. A sperm needs to be siting in the fallopian tube waiting for the egg to release. That’s why the days leading up to ovulation are so important for conception. Intercourse that happens 3 to 5 days before ovulation can provide sperm waiting for the egg to be released.

Can You Get Pregnant When You're Not in Your Fertile Window?

Yes, you can get pregnant at any time during your cycle, even during your period. If you’re trying to prevent pregnancy, this is important to know. If you’re goal is to achieve pregnancy, you’ll be more focused on the higher fertility days, but it’s good to remember that any intercourse could potentially result in pregnancy, especially if your cycles are irregular.

What Is the Time of Ovulation?

Ovulation occurs once each month usually in the middle of the cycle. To calculate the timing for you, you must know your cycle length and luteal phase length. Ovulation occurs 12 to 16 days before the next expected period. Plug your cycle and luteal phase numbers into the ovulation calculator to find out when you ovulate.

Can You Only Get Pregnant When you Ovulate?

Yes, you need to ovulate to be able to get pregnant since by definition it is the time the egg is released. A cycle without ovulation can’t produce a pregnancy. However, you don’t have to be ovulating at the time of intercourse. Since sperm can live for up to 5 days in a woman’s reproductive tract, and an egg can live for up to 24 hours, the time that intercourse can result in pregnancy is at least a 6-day window. An ovulation calculator can help you figure out what days you are most likely to get pregnant.

BONUS: Is There a Way to Increase My Odds for a Girl or Boy?

While controversial in some circles, there is some science behind timing intercourse to “sway” a boy or girl baby. Under a microscope, male sperm tend to swim faster but also die sooner while female sperm do the opposite (swim slower but live longer). So, having sex two to four days before you ovulate could slightly increase your odds for having a baby girl. On the other hand, having sex the day before or the day of ovulation may slightly increase your odds for having a baby boy. You can read more about it here.

As a side note: I had sex on the day of ovulation when I got pregnant with my son and three days before ovulation when I got pregnant with my daughter so it did work for me.

Got that BFP sign?

Either way, when you do get pregnant, head over to the due date calculator to calculate your baby’s due date!